Half-field EPR transitions (g=4.00) are observed in some synthetic carbohydrate chars prepared by heat-treatment at temperatures less than 620oC. The half-field line has a lineshape similar to that of the main resonance and about the same intensity at transverse and longitudinal microwave excitation. Its relative intensity decreases with increasing char heat-treatment temperature. In contrast, no g=4 transitions were detected for chars synthesized at temperatures greater than 620oC. The ratio of intensity of the half-field transition to that o f the main resonance is about 10-6 and does not change from 4.5 to 55 K. At 4.5 K, the g=4 line has about half of the linewidth of the main resonance. Relative intensity of the half-field signal decreases with increasing heat-treatment temperature while spin density increases. The observed half-field resonance can be explained by existence of isolated aromatic radicalclusters or by a low-dimensional spin-exchange network within the solid.